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Need OPI support for tiff images with transparencies

04-30-2008, 10:06 AM

I have a multitude of tiff images containing transparent areas. These images behave correctly when placing them in Quark or InDesign etc. But when I try to use OPI with these images, the transparencies are not transparent. They become white or some other color (depending on the colors in the tiff image). I am using the Rampage RIP and workflow. As I am fairly new to this aspect of printing, I am allowing for the possibility that this limitation is only in my head. So I ask the experts: Is this a problem that has long since been solved? Or am I correct in thinking that OPI simply doesn't do transparencies. I've deduced from the OPI spec that clipping paths (other than in the sense of cropping the whole image) must be done outside of the OPI context (at least in OPI v2.0). This would be impractical, if not impossible in my situation. Also I see in OPI v 1.3 that there is transparency support for bitmapped images but not grayscale or color images. All my images are grayscale.

OPI swap can be handled with several asset management software or simply on a folder based concept with a search feature where the software is able to descend through the main OPI high-res folder to go hunt for the high-res images ( obviously image names must be unique to prevent usage of the wrong image ).

Stef.

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How are you using OPI? I also use RAMpage but I've gone to a complete PDF workflow with it. I drop PDF's made from Native apps into RAMpage rip and make FPO's, then place the PDF FPO's in InDesign for imposition and then export that imposed plate as a PDF from InDesign CS2. CS3 doesn't support OPI in a PDF workflow tho, I found out the hard way on that one...

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Yes, we include all images in eps and pdfs fed to our Rampage system. OPI was used due to Disk space problems long ago. No need for it with the type of Terabyte sized servers now. New Rampage boxes scream now. Also, check your trap settings. Try different ones out till you get what you want.

Edited by: tlotzer on May 19, 2008 4:25 PM

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Just to clarify, if you use TIFF with a clipping path to hide the background, a proper OPI solution like HELIOS ImageServer supports TIFF/PSD images with a clipping path and the OPI resolved output will be correct – the background will be clipped away. In case the clipping path works for you the following information can be skipped.

Using transparent background images with OPI entails the following problem: Most OPI resolvers basically replace the OPI referenced image with its original image, usually during the PostScript generation. PostScript does not support transparency in color images, so using PostScript you will always receive image data with a white background. Only PDF supports transparent color images.

Using InDesign CS2/3 with placed transparent PSD or TIFF images introduces another problem inherent to InDesign: it writes no OPI comments for transparent images and embeds the placed image into its PostScript or PDF export. So no chance to generate OPI comments for transparent images here. By default, HELIOS OPI generates non-transparent low-res/layout images, which means the customer will not fall into this InDesign limitation.

Even with the current HELIOS PDF-native OPI solution, transparent images will not work because InDesign will not create OPI comments and the HELIOS PDF-native OPI resolver does not support an alpha mask for transparent images. To use transparencies within InDesign, e.g. drop shadows, assign transparency to an image box or objects within InDesign, etc. This is no problem with PDF-native OPI, only transparent background placed images will not work.

Using XPress, there is no change to use transparency in the output because XPress will flatten its generated PostScript/PDF file so that there is no transparency available anymore. This can also be verified placing the XPress generated PDF again and you will get no transparency against the background.

And now the good news: HELIOS is working on a solution to support transparent images with InDesign and the HELIOS PDF-native OPI, details will be promoted when available.

Regarding the need of OPI within InDesign, I know customers who use 500 MB image data on a single document/page where high-res PDF exporting on a 3 GHz Mac or Windows workstation takes 25 minutes. Using PDF-native OPI, the client is released in a few seconds.
Remote users will also benefit from OPI by working with low-res files. Another good reason for OPI would be re-purposing images from a central image server/library and moving the ICC color separation to the server with central settings instead of individual settings for each image within the document on each client.